1. Field of the Invention
The present invention relates to an auxiliary-device arrangement for a cylinder-deactivation multi-cylinder internal combustion engine and a cylinder-deactivation multi-cylinder internal combustion engine.
2. Discussion of the Background
Various cylinder-deactivation multi-cylinder internal combustion engines have been proposed (refer to, for example, Japanese Unexamined Patent Application Publication No. 2000-145422).
In a cylinder-deactivation mechanism discussed in Japanese Unexamined Patent Application Publication No. 2000-145422, operating cams and deactivation cams, which constitute cam surfaces at base circles not having cam protrusions, are formed side by side at valve operating cam shafts in an axial direction. In addition, operating locker arms and deactivation locker arms are provided adjacent to each other in correspondence with the operating cams and the deactivation cams. The deactivation locker arms cause intake valves or exhaust valves to open and close by contacting the intake valves or the exhaust valves.
In addition, the operating locker arms and the deactivation locker arms are connected to each other by a connection switching mechanism and operate together, and are disconnected from each other and operate independently of each other.
In the connected state, the deactivation locker arms are swung together with the operating locker arms that are swung by the operating cams, so that the intake valves or the exhaust valves are driven so as to open or close at a required timing. In the disconnected state, the deactivation locker arms that contact the deactivation cams are in an independently operating state, so that the intake valves or the exhaust valves are in a closed and deactivated state.
In an example of a multi-cylinder internal combustion engine including an OHC valve operating mechanism, an auxiliary device is driven by rotating a valve operating cam shaft (refer to, for example, Japanese Unexamined Patent Application Publication No. 10-176508).
Japanese Unexamined Patent Application Publication No. 10-176508 discusses a DOHC inline four-cylinder internal combustion engine. In this internal combustion engine, an inlet cam shaft and an exhaust cam shaft are disposed parallel to each other above a cylinder row, and a timing belt is wound upon a driven pulley (provided at one end of each cam shaft) and a drive pulley (provided at a crank shaft) to rotate both cam shafts at a rotational speed that is half that of the crank shaft.
In addition, a pump cam is formed at an end portion of the inlet cam shaft opposite to the driven pulley, and a fuel injection pump is disposed by contacting a cam lifter with the pump cam.
By reciprocating the pump lifter by the pump cam that rotates together with the inlet cam shaft that rotates, the fuel injection pump sends pressurized fuel to a fuel injection valve, so that the fuel injection valve directly injects fuel into a fuel chamber at a high pressure.
Japanese Unexamined Patent Application Publication No. 10-176508 does not discuss an internal combustion engine whose cylinders are deactivated. If the structure discussed in Japanese Unexamined Patent Application Publication No. 10-176508 is applied to a cylinder-deactivation multi-cylinder internal combustion engine such as that discussed in Japanese Unexamined Patent Application Publication No. 2000-145422 and if a fuel injection pump is disposed as in Japanese Unexamined Patent Application Publication No. 10-176508, a pump cam is formed at an end portion of an inlet cam shaft, the inlet cam shaft becomes long, and the disposition of the fuel injection pump cause the entire length of the internal combustion engine in a cam shaft direction to be increased